Does anyone why if I would take data from the STFT table in the log and use it to adjust the MAF airflow vs period table to reduce the fuel trims. It would cause FMEM in the throttle source and injector cut with fuel source. I can post the log or tune if it would help. Was not sure if it would or if this was more a general info question.
Thanks
Marty
short term fuel trims are used to make fuel trim corrections.
right. Sorry I didn't explain that well. The short term fuel trims were showing pulling like 16,18,20% out as the car is running rich. So I was attempting to correct that so it was not having to pull so much out. But when I take those numbers over to the MAF airflow vs period table and paste them in by paste with multiply % option. To reduce the fuel going in. After just making that one change to the tune I get that error I was describing. But that is exactly what my tuning book is telling me I am suppose to be doing to adjust fuel trims.
Instead of copying and pasting, try just adjusting the whole curve or parts of it by a flat percentage, like -17%. When it's that far off it's best to just move the whole thing closer, then when you get closer to +/-2% you might be able to copy paste.... If you even need to. Usually a large adjustment to the whole thing can get you very close.
ok. I will give that a try. Thank you.
As Murfie stated pull 17% fuel, what is the MAF /CAI your running. Take the Airflow side and multiply .80 is 20% & .87 for 17%.Originally Posted by mlecy
I just tried that. I highlighted everything and multiplied by .90 to drop everything by 10% just to try and move it a little. Not wanting to make any big change. It goes back to the same thing. There seems to be something else in the tune that is causing this. That get triggered when I make that adjustment. It is a JLT 123 and the MAF is just the stock 14 GT500 one. I did the advise from a previous post and got the numbers for the MAF of a stock GT500 and added 20% to try to get close to the 123. I also can't say was ok and just adding the cold air. The engine was torn down and redone with tons of changes and bolts on for the build. At one point there was thought maybe the MAF has went bad. But when you look at the log it does the MAF data moving around not like froze or stuck. So thought it was good. But could a bad MAF sensor cause something like this?
can you post your tune file? Maybe see something your not seeing..
Here it is.
What injectors are you running?
FID 2000cc injectors
If you're trying to correct fuel trims because you're trying to dial in injectors you don't need to mess with the MAF data, generally speaking you adjust your injector slope high for acceleration: wot: high load ect, low slope for cruise and idle. reduce the flow rate to add fuel and the opposite to reduce. If you do make maf adjustments make sure your maf curve does not regress at any of the column boxes/ it moves in the same direction at all times.
I tried what you said and for the low because I wanted to lean it out I increased the rate by 10 to 291.63881 from 281 but that didn't make a difference I does the same as when I adjust the MAF airflow vs period make it go into injector cut above 1200.
Last edited by mlecy; 06-03-2022 at 06:59 PM.
Im not sure you were adjusting your maf correctly as it looks like your lb/s are pretty high. If you multiply by % >Screenshot (31).png
Last edited by iceman321; 06-04-2022 at 03:16 PM.
I am sorry iceman321 I am not sure I am understand your message. I had been adjusting my MAF airflow vs period by taking the STFT from the log like you were showing in your screen shot and then pasting that into the table with multiply by %. When I did that is when I would get those FMEM errors and injector cut. But you had said to adjust the high or low slope on the injectors. Since I was trying to just get it to idle and start better with it being to rich I adjusted the low like you said. I increased the low to lean it out but it didn't like that. That is what I adjusted from 281 to 291. They are FID 2000cc injectors so they are big injectors which is why that number is pretty big.
If I misunderstood something you were saying or were suggesting please let me know.
iceman321 you were correct. I found out I had fuel hose issue and some issues with the rails. I got that fixed. I updated the low scope and it is starting to lean out I also put the old MAF table back in. Thank you for the help.
for sanity, next time you can use either STFT+LTFT or just LTFT. wideband 02's the car from factory.
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